The invention relates to audio amplifiers. In particular, the invention relates to an audio amplifier circuit for selectively clipping high amplitude, low frequency audio signals.
In audio amplifiers it is desirable to have good broad band response. It is also desirable to have the capability to adjust the high and low frequency response. This is typically achieved by means of so-called bass and treble controls or by equalizer circuits. In order to efficiently transfer signal to an output device, it is often necessary to provide amplifier circuits with an output transformer which represents an inductive impedance. The operating efficiency of an inductive impedance is adversely affected by a signal which has both a high amplitude and a low frequency. Efficient transfer of such signals demands an inductor or transformer which is much heavier than devices operating at higher frequencies and lower amplitudes. However, in order to obtain a satisfactory output signal for operating a speaker, for example, a good bass response is essential. There is thus a need for a circuit which has a reduced low frequency signal demand while maintaining full fidelity at a low signal levels.